Objective： The effect of different fermentation characteristics of Lactococcus lactis on the quality of fermented milk was explored. Methods： Fermented milk were made with 191 Lactococcus lactis strains that the flavor and taste of fermented milk were assessed by electronic nose， electronic tongue， and multivariate statistical analysis. Results： Principal component analysis（PCA） showed separation trends in the flavor and taste of the fermented milk samples by the strains that had different acid-producing rates and proteolytic activity. Mann-Whitney test showed that aromatic compounds of the fermented milk made by moderate and fast acid-producing strains more than fermented milk made by slow acid-producing strains， while opposite trends were observed in methane， ethanol and organic sulfur （P<0.01）. In terms of taste， there was strong umami of the fermented milk made by slow acid-producing strains and the more sourness of fermented milk made by moderate and fast acid-producing strains（P<0.01）. There was a significantly negative correlation between acid-producing capacity and proteolysis level（P<0.01）. Conclusion： The fermented milk produced by the fast acid-producing and low proteolysis level Lactococcus lactis had more aromatic compounds， and were sourer， while fermented milk produced by the slow acid-producing and strong proteolysis level strains had more methane， ethanol and organic sulfur， and stronger umami taste.